The separation of an individual component from a mixture can be performed by adsorption separation. To perform the separation using an adsorption separation process in a continuous manner, the process utilizes a simulated moving bed (SMB). A simulated moving bed is a technology that connects the inlet flows, or feeds, and outlet flows, or extract and raffinate, to a series of adsorption beds in sequence. These beds may be considered to be portions of a single large bed whose movement is simulated. As the separation proceeds, the inlet flows and outlet flows are shifted from one bed to the next bed in the sequence. The moving bed simulation may be simply described as dividing the bed into a series of fixed beds and moving the points of introducing and withdrawing liquid streams from the series of beds instead of moving the beds past the inlet and outlet ports.
One method of accomplishing the change of position of the inlets and outlets is the use of a complex multi-port stopcock, or multi-port valve, having four or more inlet and outlet flow lines and which are connected to a plurality of other lines leading to specific points in the adsorption bed. One type of these multi-port valves is known as a “rotary valve.”
Rotary valves are known in the art, and are described in U.S. Pat. Nos. 3,040,777; 3,192,954; 3,422,848 and 4,632,149. Processes utilizing a rotary valve in a simulated moving bed adsorption process are described in U.S. Pat. Nos. 3,201,491 and 3,291,726.
The problem with the usual rotary valves is that the valves are designed for large scale processing and are large and expensive. There is room for improvement in producing a small scale rotary valve.